This disclosure is directed to a lamp assembly, such as a lamp assembly that provides energy savings and also provides for instant light.
One proposed solution to reducing the time to full light while still obtaining the benefits of an energy savings lamp is to combine two lamps in one unit, sometimes referred to as a hybrid lamp. More particularly, a compact fluorescent lamp (CFL) and a conventional incandescent lamp are combined. Although it has been suggested to simultaneously turn on both lamps in order to result in instant light from the incandescent lamp, and then subsequently terminate or switch off the incandescent lamp to obtain the benefits of the energy efficient CFL, these known arrangements do not provide an efficient and effective manner for determining when to shut off the incandescent lamp, i.e., using the compact fluorescent lamp exclusively once the CFL has warmed up.
Before preheating is complete, there is no light emission from the CFL lamp. Once the arc discharge is initiated, the compact fluorescent lamp (CFL) still requires an additional approximately 20 to 120 seconds or more to reach full light output. During this warm-up period, there is a need for light and this is provided by the secondary light source, which in most instances is an incandescent lamp source. Once the CFL has reached full light output, there is no longer any need to operate the secondary lamp source. Therefore, when to switch off the secondary incandescent lamp source presents a challenge.
In one solution, it has been suggested that a thermally sensitive element be located in the lamp assembly, for example in the ballast compartment, to indicate when the CFL has reached a temperature indicative of sufficient light output after start-up. Unfortunately, this solution does not always provide an accurate assessment of the actual thermal conditions of the discharge vessel. Further, locating a thermally sensitive element in a lamp assembly is potentially impacted by temperature variations caused by different positions of the lamp e.g. vertically upright, horizontal, or inverted.
Likewise, other indirect factors can impact and are potentially inaccurate in defining when the light output of the primary light source (CFL) has stabilized. For example, the time to switch off the secondary or incandescent lamp source can be influenced by a random switching cycle, ambient temperature, indoor versus outdoor use, etc. As a result, the use of a single thermally sensitive element does not provide an accurate representation of the heat conditions nor does the thermal sensor necessarily provide an accurate indicator of when to terminate operation of the secondary or incandescent lamp source.
Still another proposed solution regarding when to terminate the incandescent lamp is to apply power to the incandescent lamp for a preselected time period. Again, this solution is not sufficiently accurate since various conditions may suggest a different time period, either shorter or longer.
Consequently, a need exists for a long-life compact fluorescent lamp that provides energy savings with instant light capabilities, and overcomes the problems noted with regard to turning off the secondary or incandescent light source once the more efficient, energy savings CFL source has reached full light output.